1. Field of the Invention
The present invention relates to a filter device having a housing, having at least two flow chambers separated from one another by membranes, having at least one connection for each flow chamber, and having at least one filter cap which is placed in the end region of the housing and is connected directly or indirectly thereto. Furthermore, the present invention relates to a housing of a filter device having at least two flow chambers separated from one another by membranes and having at least one end region which is connected to one of the flow chambers and is closable by a filter cap which may be put on the housing.
2. Description of the Prior Art
Filter devices of this type are used extensively in the fields of hemodialysis, hemofiltration, and hemodiafiltration. They typically include a housing in which a fiber bundle is positioned that includes multiple hollow fibers which separate two flow chambers from one another. While blood flows through the passages of the hollow fibers, the fiber outside space delimited by the chamber has dialysate flowing around it. The ends of the fibers are received in casting compounds located in the end regions of the housing. The casting compounds are typically extruded into casting caps in the end region of the housing. After sufficient hardening of the casting compound, the casting cap is removed and the cast cutting is performed, through which the fiber ends are opened. After the fiber ends are cut off, the filter caps are placed on the housing.
In previously known filter devices, each flow chamber is generally provided with two connections, through which the particular medium (blood/dialysate) is supplied and/or removed. These connections are located in the filter caps of the housing, so that the housing does not have any connections. Filter devices are also known in which the connections for the dialysate flowing around the hollow fiber bundle are positioned on the housing and the connections for the blood are positioned in the filter caps. A filter device in which all connections and/or connecting pieces are positioned in the filter caps is known from EP 887 100. In this filter device, all connections are aligned toward one side of the filter device and their center lines run parallel to one another. In this way, it is ensured that the filter device may be connected easily and reliably through plugging in to a filter or dialysis machines and/or a support in such a way that the connections or connecting pieces of the filter device form sealed connections with counter connections or counter connecting pieces.
However, a disadvantage of a filter device of this type is that because of tolerances during the placement of the filter caps on the housing, positioning problems arise as a filter device of this type is connected to the corresponding counterparts. These may lead to an optimal sealed connection not being provided between the connections and/or connecting pieces of the filter device and the corresponding counterparts, which may result in unsatisfactory functioning of the filter device and endangerment of the patient.
In order to avoid problems of this type during the positioning, it is suggested in EP 887 100 that the spacing of the connections of the holding part receiving the filter device be positioned precisely using a centering pin of the holding part in such a way that this spacing corresponds to the spacing of the connections on the filter device. Reliable connection is possible in this way, however, correction of this type is comparatively complex.
A filter device is known from U.S. Pat. No. 4,211,597 which does not include a housing and filter caps placed thereon, but rather two halves which are connected to one another in the lengthwise direction and receive the hollow fiber bundle. During the production of filter devices of this type, the filter housing is manufactured first and the hollow fiber bundle is manufactured separately therefrom in separate work steps. In a further manufacturing step, the hollow fiber bundle is placed in the housing halves and these halves are connected to one another fluid-tight.
It is the object of the present invention to refine a filter device according to the species in such a way that the positioning problems cited during the placement of the filter device on a holder do not occur.